| 摘要 |
PROBLEM TO BE SOLVED: To reliably/surely update a media key block (MKB) on a recording medium and an intermediate key encrypted by an authentication key. SOLUTION: An effective information processing section (11) refers to effective information (221) on a recording medium (20) to determine effective MKB (211) and intermediate key (222) and when ineffective MKB (211) and intermediate key (222) are rewritten, the effective information (221) is rewritten. An MKB processing section (12) reads out the effective MKB (211) to perform update processing on an MKB (101) and rewrites the ineffective MKB (211). An intermediate key processing section (13) reads out the effective intermediate key (222) for decryption and re-encryption using an authentication key (103) and rewrites the ineffective intermediate key (222) into the re-encrypted intermediate key. COPYRIGHT: (C)2010,JPO&INPIT
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